ASoC: Select core DMA when building for S3C64xx

Ensure that the core DMA support is available when building for
S3C64xx.
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/s3c24xx/Kconfig

 config SND_S3C24XX_SOC
 	tristate "SoC Audio for the Samsung S3CXXXX chips"
 	depends on ARCH_S3C2410 || ARCH_S3C64XX
+	select S3C64XX_DMA if ARCH_S3C64XX
 	help
 	  Say Y or M if you want to add support for codecs attached to
 	  the S3C24XX AC97 or I2S interfaces. You will also need to